


A Perfect Pair

by MeGaLoTrash



Series: Corrupting Innocence [2]
Category: Undertale (Video Game)
Genre: Alternate Universe - Swapfell (Undertale), Ectobiology, Established Relationship, Experimentation, Fashion Disaster Papyrus, Lactation Kink, M/M, Mapleblossom - Freeform, Masturbation, Multiple Orgasms, Overstimulation, Possessive Behavior, Rough Sex, Semi-Public Foreplay, Teasing, Topping from the Bottom, ecto-breasts, innocence kink, papcest - Freeform
Language: English
Status: Completed
Published: 2019-05-23
Updated: 2019-05-23
Packaged: 2020-03-13 06:05:41
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 9,234
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18934948
Author URL: https://archiveofourown.org/users/MeGaLoTrash/pseuds/MeGaLoTrash
Summary: A follow up to 'Coveting innocence'A few months down the line, a more established relationship, a weekend away that presents an opportunity for Papyrus to experiment with a different ecto-body.Hope you guys enjoy, I really loved writing this one!





	A Perfect Pair

**Author's Note:**

  * For [Silver_Centurion](https://archiveofourown.org/users/Silver_Centurion/gifts).



Papyrus looked from side to side, giving the crowded hotel lobby another once over. On finding nothing out of the ordinary, again, he finally decided it was safe to do what he’d spent hours rehearsing. 

Which was slipping one of his hands into Slim’s own. 

Slim stiffened for a second, almost making Papyrus want to forget the gesture entirely. It took a few moments for Papyrus to remind himself that Slim hadn't been the one stressing about the 'right moment' to do this. Slim wouldn’t be used to Papyrus making the first move, especially not when they were in public. He just had to remember to keep calm and not freak out. Thankfully, Slim’s initial shock didn't last long. He squeezed Papyrus's hand and gently pulled him closer, so that Papyrus could subtly lean into his side. 

Papyrus breathed a sigh of relief. He was still nervous about any kind of public affection, in _his_ universe nonetheless. He knew he’d be the topic of hot gossip for weeks to come. Thankfully his urge to snuggle into Slim was stronger than any threat of embarrassment. 

_This was nice._

They were stood in line for the front desk at the MTT resort, planning to book a romantic night together for the coming weekend. It was too extravagant for Papyrus’s usual tastes, but had been three months since he started dating Slim, and that was cause for celebration. Well, it was three months since they started dating officially. They had tried to keep things secret initially, knowing their brothers wouldn’t approve. That secret only lasted a few weeks, ending with hurried explanations as to why their brothers had caught them making out on the couch. Black had been confused, Sans was more than a little angry, and there were a few harsh words tossed around before Papyrus managed to de-escalate the situation. There were a lot of reassurances on Papyrus’s part, and promises from Slim about his intentions, but both brothers did begrudgingly accepted the budding relationship. 

Papyrus was happy, but there wasn’t a day that went by where he didn’t thank his lucky stars that making out was the only thing they’d seen. If Sans or Black had caught them the first time they’d done things on that couch… then he doubted that Slim would be allowed within two universes of this one. 

Their relationship had started in a whirlwind of passion. It wasn’t planned, and it went against all the guidelines in Papyrus’s dating manual. The growing tension between them just happened to come to a head when one of their hangout sessions turned _very_ lewd. Looking back, they’d been getting closer and closer under the guise of friendship at a very rapid rate. Papyrus had tried to bury his feelings, thinking he was misunderstanding a more platonic affection. Even so, it took him far too long to realise Slim was attempting to turn one of their cuddling sessions into something more. Papyrus had been so aroused, he couldn’t control himself. He went along far too eagerly, and when he felt his body lock up with his first real orgasm he was sure he’d ruined their friendship for good. 

Slim had torn off his shorts without a second thought, burying his face in Papyrus’s magic and effectively silencing any anxieties Papyrus had. 

Just thinking about that afternoon made Papyrus’s skull heat up as they moved forward in line. He could remember how amazing Slim made him feel, how he’d begged and screamed as he was made to cum over and over. Slim hadn’t been disgusted when he’d made a mess, nor had he cared about his lack of experience. In fact, it seemed to endear him even more. Slim had claimed him in a ways Papyrus never thought possible, breaking the last shred of his self-control as he all but begged him to stay at the end. That didn’t put the other skeleton off either. Papyrus would remember that love-struck look Slim gave him until the day he died. 

With such an explosive start, it should have been much less of a surprise that they found the secret hard to keep. After those initial weeks of sneaking around and being intimate with each other at any given opportunity, and subsequently getting caught, they tried to keep things a little more low key. Sans and Black might accept their relationship, but they didn’t need to make them even more uncomfortable by flaunting it. 

So, at Papyrus’s suggestion, they tried to keep things platonic when their brothers were in the house. When that didn’t last, they slipped into an unspoken rule of only doing things when they were asleep with the door bolted and a hand firmly over Papyrus’s mouth. No matter what they tried, Papyrus was never going be the silent type. It was bearable at first, and Slim did his best to stick to the new rules, but Papyrus knew it couldn’t last. They craved more than stolen kisses and hushed fumblings in the dark. It was one of the reasons Papyrus had suggested the discreet weekend away, so they could spend time together without worrying about being interrupted. 

Plus, the hotel’s main selling point was their soundproofed rooms. 

“Welcome to the world famous MTT Resort, how can I help you today?”

Papyrus snapped out of his daydream. He hadn’t noticed they’d reached the front of the line, and now both the receptionist and Slim were waiting expectantly. Nerves made his smile too wide and almost made him trip over his own feet as he stumbled over to the desk. 

“WE’D LIKE TO BOOK A TABLE AND-”

Papyrus felt his skull flush as he forced himself to pause. He had all but yelled at the receptionist, causing the fingers on her head to visibly recoil. Not only did he feel awful, but he’d been seconds away from broadcasting the intimate plans he’d made with his boyfriend to the whole lobby. 

_So much for being discreet…_

“Sorry- and we’d like a room. For the weekend? I have the-um- premium membership card.”

“Certainly!” The receptionist beamed, snatching Papyrus’s card from his fingers scanning it, causing her computer to play an embarrassingly loud fanfare. “It'll take a few minutes to assemble your VIP package and print you unique key-cards, MTT only wants the best for his biggest fans.” She stood to her feet, retrieving a few pieces of glittering golden paper from a box on the wall, “While you wait, here are a few vouchers for 10% off Glamburger specials.”

Papyrus cringed, painfully aware of how many other guests were still watching them after the scene he made, “Oh that's not-”

“It's part of the package, Sir.”

The coupons were then waved close to Papyrus’s face, giving him no choice but to take them and leave before his skull was blown clean off his shoulders. Slim followed suit, a knowing smile already working its way on his scarred features. 

“Sorry, I didn't expect it to be like that, or I would have done it online.” Papyrus murmured while they walked across the lobby, desperately trying not to make eye contact with anyone who’d witnessed the commotion. “Are you ok? If it’s too much, we can-”

“-You worry too much, Papy. Come here.”

It wasn’t a question. Slim pulled him close and pressed their teeth together before Papyrus had a chance to react. Papyrus’s mind was screaming at him over making even more of a scene, but luckily what his soul wanted was drowning that anxiety out. It wasn’t officially their weekend away, but their brothers weren’t around, and Papyrus was starving for attention. He melted into Slim’s arms as they deepened the kiss, safe in the knowledge that a little PDA wouldn’t kill anyone. 

Even with his sockets closed, Papyrus knew Slim was revelling in the attention. In this universe, Slim was used to people staring because of his height and intimidating appearance. But it never bothered him in the slightest. Papyrus was sure if his boyfriend had his way, they would have skipped the whole hotel room and had his way with him right then and there. Slim didn’t care what other people thought, which was a refreshing change to how much Papyrus worried about everything. He wished he had more of Slim’s ability to throw caution to the wind, knowing that he’d enjoy the results of being a little less uptight. Papyrus was pretty sure he’d still draw the line at Slim tearing off his clothes and pounding him hard on the MTT fountain though. Even if that mental image was straight out of his most secret fantasies. 

Papyrus was starry-eyed and whimpering when Slim pulled back, happily letting himself be led the rest of the way towards the burger stand. A few monsters were gathered around, either waiting for their order or socialising in small groups. One Monster in particular caught Papyrus’s eye. Catty was leaning over the serving counter, trying to keep the attention of a jittery looking employee. The usual overalls she wore were nowhere to be found, though. In their place was a tight fitted glittering bodysuit, complete with glam makeup look and stiletto heels. She looked absolutely amazing in Papyrus’s opinion, and to top everything off, she was wearing the coolest leather jacket. Which he immediately coveted, of course. 

Papyrus had seen a few Monsters dressed similarly tonight, making him wonder if there was an exciting event on at the capitol he hadn’t heard about. He filed that away for future reflection since there was something much more interesting that caught his attention. He hadn't been able to tear his eyes away from Catty, for more than one reason, and he soon discovered he wasn’t the only one. Slim was just as enamoured with her beauty, if not more so. But while Papyrus was admiring her beauty and overall, it was pretty obvious where Slim’s attention was focused on. 

Catty’s _impressively_ large chest. 

Her breasts were outlined perfectly in the bodysuit with ample cleavage showing at the top, and Slim couldn’t tear his eyes away. With the height of the counter, it presented a perfect shelf for her to lean over and torment one of the staff members. It was clear she knew exactly what she was doing, giggling at the way the server was fumbling over his tasks and shooting the two Skeletons a flirty wink. Slim averted his eyes when he was caught staring, a heavy blush finally covering his skull. Rather than be jealous, Papyrus’s soul couldn’t stop flipping in his ribcage at such a sight. 

Papyrus wasn’t a hypocrite. He knew wandering eyes didn’t mean Slim was falling for anyone else, just like he wasn’t ready to leave Slim the moment he started admiring another monster. No, Papyrus instead saw this as a golden opportunity. They placed their order, watched as the server fell over his words in an effort to keep his cool in front Catty, all while Papyrus felt the cogs whirring in his mind. 

If breasts were Slim’s thing, then Papyrus would be more than happy to try to fulfill those desires. 

While they finished their burgers and went to collect their key cards for the weekend, Papyrus was already well on the way to formulating a plan. Tomorrow was their first night at the hotel, meaning he had tonight and tomorrow day to try and adapt his magic. Papyrus knew it was in the realms of possibility. Magic was incredible, and even though Papyrus was new to using it in sexual situations, he was filled with determination. He’d seen some of his alternates fill out their clothing in different ways, and he’d already managed to form different genitals with Slim’s help. Plus, trying something new wasn’t going to cause him any harm! Papyrus let Slim walk him most of the way home, stole a few more kisses, and left with promises to make this weekend an unforgettable one. 

Papyrus tried his best to act as normal as possible throughout the rest of the evening. He knew Sans didn’t approve of his weekend away, so he tried to keep his bursting levels of excitement to himself. Where Black had grumbled about him and Slim dating and then moved on, Sans wasn’t able to let things go as easily. He didn’t protest when Slim came over anymore, but he’d still watch him closely to make sure he didn’t do anything he deemed inappropriate. Papyrus couldn’t blame his brother for being on high alert after the makeout incident, but there had to come a time when Sans accepted he was in a serious and mature relationship. Especially since Sans was no saint himself. Still, Papyrus knew he couldn’t start asking questions about how to manipulate his magic if he didn’t want his brother to have an aneurysm. 

He needed to wait for Sans to fall asleep, preferably downstairs and as far away from Papyrus’s bedroom as possible.

A small cheer was all Papyrus allowed himself when he saw his brother’s sockets slipping closed. This was the easy part, the real challenge was yet to come. When Papyrus closed his bedroom door he locked it immediately, just to make doubly sure he wouldn’t be interrupted. He quickly shed his clothing, making sure to fold the items neatly even though his body was shaking with anticipation. Papyrus turned a little sheepish when it came to approaching his mirror, shy about seeing himself stripped down and knowing what he was about to do. But he wanted to give himself the best chance at forming things, and a visual aid would help him make sure he was doing everything correctly. Even if his reflection was a stark reminder of the brightly glowing blush all over his skull. 

Papyrus wasn’t sure what he expected to achieve by intensely focusing on his ribcage alone and then willing his magic to move upwards. He still sighed in frustration when nothing happened. He could feel the unsatisfied magic in his bones from being with Slim earlier, so it wasn’t like the potential to form something wasn’t there. Instead of letting his doubts consume him, he took in a calming breath. He just needed to try a different approach. Papyrus thought back to how Slim had helped him and eventually realised why he wasn’t going anywhere. He needed stimulation first and _then_ he could try moving that excited magic upwards. 

Meeting his eyes in the mirror almost put Papyrus off completely though. Before being with Slim, he’d only experimented with a handful of times. It had never felt right, and the guilt over doing something ‘wrong’ had made it impossible to continue. Even now, the only times he really felt a desire to masturbate was with assistance. Like the times where he and Slim couldn’t meet up and had to resort to talking to each other on the phone. Slim knew exactly how to make Papyrus cum without even needing to be in the room, but Papyrus didn’t have the luxury of his boyfriend’s honeyed words now. Not if he wanted to keep the surprise. Papyrus tried to calm himself down and remember that there wasn’t any pressure for him to climax. He had a reason for doing it, a different goal in mind. This was nothing for him to feel shame over anymore.

After glancing at the door for the tenth time, just to make sure he locked it, Papyrus pulled his desk chair over to the mirror and sat down in front of it. He thought it was a good idea to have some stability with the way his limbs were already threatening to buckle underneath him. He relaxed into the chair and let his sockets slip shut as one of his hands reached up to touch his ribs. It felt better than he anticipated, and Papyrus knew he was on the right track went sparks of magic licked the tips of his phalanges. But he was going to need to do much more if he wanted any real results. Papyrus let his mind wander naturally, not fighting his imagination when his last time with Slim popped into his mind.

_Papyrus’s hand was the only thing stopping him from letting the whole world know just how incredible he felt. Slim had him bent in half on the bed, slamming into his wet pussy like their lives depended on it. They had to be quick; only having ten minutes before Sans was due home. Despite knowing this, the fire in Slim’s eyes only grew with every thrust. He wanted Papyrus, wanted to be as close to him as physically possible, was biting and clawing at everything he could reach, just to mark Papyrus as his._

Papyrus gasped, feeling an influx of magic rushing around his bones. He could feel weight in his pelvis, tempting him to form his pussy again so he could relive that fantasy. But he stopped it just in time. Papyrus willed himself not to form his magic just yet, remembering why he was doing this, focusing instead on sending all that energy upwards. He kept his fingers steadily tracing across his ribs, the little jolts of pleasure giving that unformed magic a signal of where to head to. It took a bit of patience, but eventually magic travelled up his body and became a tangible but formless mass.

For the first time since he started, Papyrus looked at himself head on in the mirror. He already looked pretty far gone; his sockets were lidded, his mouth hanging open lewdly with a line of magic dripping from his tongue. But what he was really interested in was watching and helping the mass of magic take proper shape. Papyrus tried to relax, moving his hands off his ribs, lightly shaping the magic that he wanted to form. It was too much. Touching his magic like this felt like touching a raw nerve, and Papyrus had to slam both hands over his mouth to keep from screaming. His eyes rolled in his sockets as he squirmed in his seat, desperately trying to calm himself down. It took a while, but he refocused on keeping his breathing slow and steady until it felt safe to continue. 

Papyrus planned to give himself a break before trying again. But his sockets snapped open when his hands left his mouth, coming into contact with two mounds of magic on their way down his body. 

Two _very_ large mounds.

The shock that he’d succeed in channelling his magic both correctly and smashed his expectations was hard for Papyrus to comprehend. He stared at his reflection, taking in every detail of the ecto flesh sitting comfortably on his chest. He stood from his chair, turned this way and that while watching himself in the mirror with a steadily growing grin. It was hard to believe they were real. It felt strange for Papyrus to be admiring himself naked, but he couldn’t deny the feeling that breasts _really_ suited his body. They looked good, and they made him feel good too. Papyrus’s hands hadn’t ever left his chest, and now the urge to really explore his new magic hit him hard. He indulged for a second, keeping his eyes on his reflection as he let his hands ghost around his breasts towards his newly formed nipples. 

“Oh! MMmm-” Papyrus moaned softly, moving his fingers in small circles as a shiver went down his spine, “Wowie.” 

The ripples of pleasure were felt all over Papyrus’s bones, causing the rest of his magical body to form with a soft pop. This included the pussy he’d denied himself earlier, already slick with arousal. Papyrus’s inhibitions were lowered by the slow build up, meaning that he didn’t think twice about moving one hand between his legs too. He squirmed against the fingers parting his folds, almost losing himself to the pleasure when a stray clear thought entered his clouded mind. If he waited, and explored the new parts of his body with Slim like he planned, then he knew it was going to feel even better. 

With a shaky sigh, Papyrus stopped the movement of his hands and walked over to his bed. 

It felt too risky to put on nightclothes with how sensitive his body was right now, so he opted to sleep nude instead. In the back of his mind, he knew there was a chance Sans would teleport into his room to check why it was locked, but apart from the unworn pajamas there really wasn’t anything suspicious in his room. Papyrus had the sense to grab his phone on the way to his bed though, and couldn’t resist the temptation to shoot Slim a quick text saying how excited he was about tomorrow. The reply was instant, and very suggestive, making Papyrus giggle as he snuggled into his blanket. 

A few more texts and Papyrus fell asleep with his body still formed, a huge smile plastered across his face as the details of his master plan fell into place. 

The next day was torture, to say the least. While Papyrus’s body had dissipated overnight, that excited magic didn’t leave his bones. It hummed uncomfortably and made him extremely aware of every part of his body. Which made breakfast extremely awkward. Papyrus knew his brother had no way of knowing what was going on underneath his clothes, but this heightened state made him feel exposed nonetheless. Not to mention Sans’s insistent questions and not-so-subtle digs at Papyrus’s chosen date mate. Papyrus was already frustrated but knew he needed to keep his mouth shut if he didn’t want to start a fight before his weekend away. He took solace in finding a silver lining; at least Sans was finally acknowledging that he was dating Slim now. 

Speaking of Slim, Papyrus couldn’t resist but couldn’t resist texting him a few times during the day. He tried to keep his cool and keep his mind focused on other things. But with each text a little more flirty than the last, Papyrus was sure his skull was flushed for the majority of the day. 

Slim would usually pick Papyrus up at his house first when they went out together. That was the default plan for today too, before Papyrus had a stroke of genius, asking Slim to check into their room first and he’d meet him at the resort instead. It was an innocent sounding request, one that Slim agreed to without a second thought, but Papyrus’s soul was hammering in his chest all the same. Rather than leaving everything to the bedroom, he wanted to try making the date extra special too. The best way to show off his new body would be to turn up with it formed from the start, wearing something that would really show it off. Papyrus was beside himself with excitement. It was so unlike him, to want to be the center of attention and watch Slim’s jaw drop to the floor. And it was more than that too. 

Part of Papyrus, a part he never knew existed until recently, wanted the opportunity to tease and seduce Slim for once. 

Papyrus had a few outfit ideas lined up for the weekend, but they were all planned without his new assets in mind. He went to his wardrobe and flicked through his clothes, almost burst from excitement when he spotted a button up cream blouse. He’d have the opportunity to look sophisticated for dinner and then perhaps loosen some buttons later to try and entice his boyfriend. It wasn’t what he’d initially planned, it was even better! Papyrus grabbed the shirt as well as a pleated skirt and his favourite platform boots. He also picked a pair of cute panties and matching long socks, giving him a sneaky excuse to have his body formed from the get-go if asked. They’d only fall down otherwise, and this way it would provide Slim with a peek of ecto between his skirt and socks. 

The giddy energy was palpable in the bedroom as Papyrus took off his regular clothing and focused on forming his whole body. It was considerably easier the second time around, with only a little stimulation to his ribs needed to coax the magic on his chest to form again. Papyrus knew it was because he was still buzzing from last night, and the anticipation made him want to redress as quickly as he could. He only slowed down when it came to buttoning up his blouse, knowing all too well that he could risk exciting himself more if he wasn’t careful. The first few buttons were done without any hassle, but Papyrus really had to strain and push his breasts together to do the rest of the blouse up. He had to leave the top two undone completely with the third still looking strained no matter what way he posed. _Which wasn’t necessarily a bad thing._ Papyrus looked himself over again in the mirror, admiring how appealing his new body looked and how he’d picked a great outfit to show it off. 

Despite this, it still felt like something was missing. 

Papyrus went back to his wardrobe, scratching his skull as he tried to figure out what extra element would bring the outfit together. He looked over some accessories, but none of his badges or shades were the right bit of pizazz he was looking for. He’d almost given up the search when he spotted it. At the back of his wardrobe was a jacket; blue denim with a selection of awesome patches he’d sewn on over the years. Catty had worn a jacket with her outfit, so obviously that meant cool jackets were on trend at the moment! And it gave Papyrus a way to conceal chest until he met up with Slim. He couldn’t believe he’d forgotten about it, especially when he put it on and realised it had been precisely what he’d been looking for. He even took the time to silently thank his past self for sewing on matching fireballs on each side of the jacket. 

Papyrus became even giddier, jumping and clapping his hands with unbridled joy. He looked so unbelievably cool that he was sure Slim wouldn’t know what to do with himself!

As if through some psychic link, Papyrus heard his phone vibrate with another text. Slim had checked into their suite and would wait for Papyrus outside the resort when he was on the way. The temptation to just fling himself out the door and sprint there was hard to resist, but Papyrus once again reminded himself of the value of patience. He went through his overnight bag, making sure he had everything he needed for the dozenth time that day before pulling it closed. He gave himself one last check in the mirror to make sure his jacket covered his chest fully before heading back downstairs.

Sans was on the couch watching one of MTT’s specials as he flicked through his phone, making Papyrus momentarily panic. He needed to get past him to leave through the front door, obviously, but he couldn’t figure out if sneaking by or acting like nothing was wrong would raise the least amount of suspicion. The choice was taken out of his hands when Sans raised his head and did a double take. 

“ _That’s_ what you’re wearing?” 

Papyrus let out a small sigh of relief. For a moment he thought Sans had seen the outline of his breasts and that he’d have some very fast explaining to do, but instead, it was merely his brother’s inability to know good fashion when he saw it. Nothing new there. 

“Ye-yeah, it is!” Papyrus replied, pulling his jacket across himself to show off the patches and hide the shape of his chest even further, “Pretty rad, right?”

“The raddest,” Sans added with a smirk before turning back to the T.V. “Have fun Paps. And uh- don’t do anything I wouldn’t do.”

 _So... anything is fine?_ Papyrus bit his tongue and smiled through gritted teeth. A lecture in hypocrisy was certainly not what he wanted to launch into right now. 

“Thank you, brother!” Papyrus’s grin only grew as he walked towards the door, making sure to wait until the last second before adding something he knew Sans would have a hard time ignoring all weekend, “I’m sure I’ll have an absolutely _wonderful_ time alone with my boyfriend.” 

Papyrus closed the door behind him without another glance back at his brother. It was an abrupt and petty way to end their conversation, but he’d heard enough passive-aggressive comments that it felt very much deserved. Respecting Sans’s comfort levels and not doing anything with Slim in his presence was one thing, but he was done pretending his relationship didn’t exist. With a spring in his step, leaving his worries behind, Papyrus walked towards the Riverperson’s boat. 

It was either nerves or a pure coincidence, but Papyrus would swear that boat journey took literal years. He was unable to keep still, anticipation shooting around his body from the top of his skull to the tips of his phalanges. He about asking the Riverperson what they thought of his outfit, or asking for relationship advice, anything that might provide a bit of light distraction. But he doubted he’d get any clear answer out of them. Papyrus usually revelled in their riddles, but his nerves were cutting off most of his cognitive ability. It was probably for the best, all he could focus on was the plan he’d been perfecting since last night. And how close it was to becoming a reality. 

As he got closer to Hotland Papyrus soon realised his jacket was only going to make him sweat more than the nerves in this heat. He experimented with wearing it open, then having it looser on his shoulders, before taking it off altogether when he stepped off the boat. He was bummed out at the thought of holding it when it really completed the outfit, so instead tied it around his waist. Immediately Papyrus noticed how that tugged his blouse down, accentuating his breasts even more. With Slim so close, it couldn’t have been a better solution to the problem, giving him a much-needed boost in confidence. There weren’t too many monsters around Hotland at this time of day, so Papyrus felt no shame in strutting towards the elevator like he owned the place. 

When Papyrus started heading towards the hotel, another wave of panic hit him. What if Slim didn’t like his outfit, or worse, thought his new ecto body looked ridiculous. He was about ready to turn around and go home when he caught sight of Slim leaning against the wall outside. It seemed Papyrus wasn’t the only one who’d made the effort tonight. Slim’s oversized coat was gone in favour of a sleek black shirt and pants, almost making him blend into the shadows. But there was no mistaking the glint of his fangs and the glow of the filter when he took a drag of his cigarette. If Papyrus wasn’t so set on his plan, he’d be swooning. As luck would have it, Slim was yet to notice him. Which gave Papyrus a perfect excuse to push down any lingering anxieties and make a big entrance. 

“Oh! Slim!” 

Papyrus waved frantically until he caught Slim’s attention before immediately breaking into a run to close the gap between them. It was the sort of thing he always did when greeting friends, but he realised all too late that he’d not factored in his two new problems. Papyrus almost recoiled as he felt his chest heave and bounce while he ran, making him question why the idea of purchasing a bra never entered his skull. Still, despite being uncomfortable, it was more than worth it for Slim’s reaction. Papyrus watched Slim go through recollection, saw his eyes darting downwards, and then witnessed the cigarette falling out clean of his mouth. 

Slim wasn’t given chance to process what was going on before Papyrus reached him and enacted the second part of his plan. To pull Slim into the tightest hug possible. Slim might’ve been larger in both frame and height, but Papyrus focused all his attention on wrapping his arms around his boyfriend’s ribcage. The loud wheezing sounds coming from Slim when their chests were pressed flush together only made Papyrus squeeze him harder. He could feel his skull heating up at the feeling of his already sensitive nipples pressing against the hard bone of Slim’s ribcage, but it was worth bearing for such a visible reaction. Slim’s hardly ever cracked outside the bedroom, so the strained noises were music to Papyrus’s acoustic meatus. 

_And this wasn’t even half of what he had planned…_

Papyrus pulled back from the hug, waited for Slim’s eye lights to flick downwards, before asking, “Do you like them?” In the sweetest voice that he could muster.

Just as Papyrus expected, his boldness was utterly unexpected and threw Slim for a loop. 

“Wha- I- um-” Slim coughed, trying to give himself a second to calm down from his inner turmoil, “What?”

“My Boots? Or were you looking at the cool flames on my jacket?” Papyrus added, turning this way and that to show everything off while Slim’s skull rapidly turned a dark shade of amber, “You’re welcome to borrow either any time you like!” 

Papyrus kept grining despite knowing this was the moment that would make or break his masterplan. There was a chance Slim would see right through his innocent act and call him out right here and now. He’d bet everything on knowing his boyfriend a little better though. Slim was the first monster to not automatically treat him like a child, but that didn’t mean he’d be able to resist Papyrus’s charms with his attention pulled elsewhere. Slim averted his eyes, evidently too distracted by his own perversions to realise he was playing right into Papyrus’s hands.

“Oh er- they’re- yeah, they’re great-” Slim mumbled in the most unsteady voice Papyrus had _ever_ come out of his mouth, “You look good too. Are you not-um- cold?”

 _Ah._ Papyrus didn’t need to look down to figure out why Slim had said that. He knew the brief amount of stimulation had made his nipples hard, and the blouse would be doing little to hide the obvious protrusions. Slim was giving him a polite opportunity to acknowledge what his body was doing, but Papyrus didn’t want to break the act. No, if he was playing the oblivious angle tonight, then he needed to be 110% committed to it. Plus, the beads of sweat trickling down Slim’s skull and the glow of his own body forming were a dead giveaway he was really into this. 

“I feel great!” Papyrus beamed, acting completely unphased before offering Slim his arm, “Shall we?” 

It was hard to ignore the reactions from the other guest as they made their way through the lobby the restaurant. Unlike before, where the stares and whispers had made him uncomfortable, Papyrus felt more confident than ever. This was that carefree feeling he’d been searching for, the one where he no longer cared about what was being said about him. It did help that it sounded overwhelmingly positive too. Those that knew him wondered how he’d made himself look so good, and those that didn’t know him were asking how they could. But Papyrus only had eyes for one monster. At the moment, Slim looked like he was being torn between showing Papyrus off and the more primal instinct to keep Papyrus all to himself. Not to mention he was sweating buckets by the time they were seated at their table. The sheer effort of hiding arousal and preventing anything from forming was a struggle Papyrus knew all too well. 

_Was it too much?_ Papyrus tried to pretend like everything was fine when they were handed their menus, but he couldn’t help worrying that he’d gone too far. His top felt a little too close to bursting with the size of his breasts, and the height of the table only drew more attention to his prominent cleavage. Even their waiter hadn’t been able to keep his eyes at skull level at he was only there for a moment. So Papyrus could only imagine what torture his boyfriend was going through, especially when it would be a few hours before he could get his hands on Papyrus’s body. He was about to cave and call everything off for the second time that night when he caught Slim’s expression over the top his menu.

Slim had been watching him like a hawk the entire time. That wasn’t unusual. What was different was how visibly affected he was. It wasn’t just the sweating or the flushed skull, it was the fact Slim looked was seconds away from snapping. Slim wasn’t shy in the bedroom or out of it, but everything he did always came across as planned and premeditated. This was a side of him Papyrus had never really seen, one where Slim found it hard to hide his true intentions. Papyrus couldn’t imagine _half_ of the dirty things going on in Slim’s head right now.

But _gods_ , did he want to.

Papyrus knew Slim held himself back when they were together purely for his benefit. And since their first time, Slim had Papyrus with a level of care never found in his own universe. Papyrus loved Slim for it, more than he could ever verbalise, but he didn’t want his boyfriend to hide some of his aggressive urges all the time. Not when they were channelled into the bedroom at least. Papyrus wanted to know what Slim was truly like when his façade was dropped and wanted Slim to know he wouldn’t push him away either. In fact, Papyrus was sure he’d enjoy the results. 

And now he had the perfect opportunity to try and coax that side out.

As soon as the waiter left with their order, Papyrus started to push the boundaries on what he could get away with. He told Slim about his day, and about all the things they could do tomorrow now they were closer to the capital all while talking with his hands. He waited until he had Slim’s undivided attention before slowly moving his hands lower, making it so his boyfriend had no choice but to notice his chest again. Slim’s eye lights went wide when he realised where he was staring, and Papyrus added insult to injury by not-so-subtly pushing his chest out. The torment didn’t stop there though, Papyrus leaned forward on his seat while he kept talking, making his chest rest perfectly on the table without missing a beat in the conversation. 

Slim’s eyes darted up to meet Papyrus’s own, sheer disbelief that Papyrus could be this oblivious evident on his features. It would have been easy to cave right there and then. To give Slim the satisfaction of figuring him out with the promise they’d be able to resolve everything as soon as they got back to their room. But Papyrus wasn’t done. There was no denying he was on a power trip over finally having the upper hand. He carried on like everything was normal, masking his true reactions behind and unwavering smile. Like his newly formed breasts weren’t resting on the table within Slim’s reach. 

Slim went from a from sweaty, nervous wreak to looking like he was about to break everything in the room out of pure frustration. Papyrus was sure he’d be footing the bill for the marks Slim’s fingers were already making in the table as he tried desperately to regain control of his reactions. It all had nothing on the predatory look in Slim’s face though. His gilded fangs were glistening with saliva, which coupled with the growly tone he couldn’t shake from his voice made him seem practically feral. Papyrus’s body was reacting just as strongly, his increasing need to have Slim inside him almost making him rock in his seat. But he stopped himself. He didn’t want to give Slim a hint of recognition yet. He watched Slim wipe away his drool, only making an offhand comment about being sure they didn’t have too much longer to wait on their meals. 

_Slim did look famished after all…_

There was still a part of Papyrus that felt guilty about teasing Slim like this. In public no less. But another part of him knew the ends would justify the means. Papyrus thought back to all the times Slim had teased him for hours, keeping him on the edge of climax until there were tears in his sockets. It was about time Slim got a taste of his own medicine. Their meals arrived all too soon, acting as a distraction for Slim and a way for him to calm down. For Papyrus, they were only extra tools to continue tormenting his boyfriend. Papyrus started with his drink first. He made sure Slim was watching him again before wrapping his tongue around the straw and sucking loudly. He’d seen a similar move in one in a cheesy romance film, and Papyrus even added the part where he looked up at his boyfriend with lidded sockets. He didn’t pull it off as elegantly, but Slim’s choke in response was exactly the reaction he’d been waiting for. 

With the food, he couldn’t do as much without making a mess. But Papyrus refused to be beaten by a such a trivial practicality. He ate a mouthful of pasta next, went over the top with his reaction to how good it was before getting another forkful and leaning over the table for Slim to try it. Slim would never refuse him, and he knew Slim wouldn’t be able to resist the perfect view down Papyrus’s top either. Papyrus was smiling even wider than before as Slim regarded what he was being offered, his soul fluttering when he ate it in one bite. 

That was when everything changed. 

Slim took the bait just like Papyrus thought he would, but there was something different about him when he finished eating. It was like a switch had been flipped, with a smirk Papyrus knew all too well forming on Slim’s darkened features. There was something in his eyes too, something very dangerous. Papyrus didn’t dare break eye contact until he was sat back in his seat and knew the rising blush on his skull was tearing down everything he worked towards. He expected to be berated, not to have Slim grab one of his hands and all but force Papyrus to look at him again. 

“Thank you, Papy,” Slim purred, stroking the trapped hand with the tips of his phalanges in a way that made Papyrus shiver, “That was _delicious_.” 

_He knows_. Papyrus tried to smile and carry on with his meal but found it hard to finish anything with the rising panic. Slim wouldn’t let him go even as they continued to eat, the dangerous aura of magic around him growing stronger by the second. Papyrus wasn’t sure if he needed to be legitimately afraid or if the slickness between his legs was his body’s way of telling him what was to come. He was so close to whining with how intense his need for his boyfriend was. If dancing with danger for three months had taught him anything, though, it was that this was far from over.

Slim took his time after finishing his food, letting Papyrus stew in confusion until he was ready to leave. He waved the waiter over without taking his eyes off Papyrus, the growing fire in his eyes the only indication that the cogs were turning rapidly. Slim was back in the driver's seat again, and Papyrus could only buckle in for the ride. 

“Please add the cheque to our room bill.”

The Waiter smirked, knowingly, collecting their plates before adding, “Certainly, Sir.”

Papyrus gulped as Slim’s smirk grew wider, fully exposing his sharpened fangs again. He knew what he was in for, and yet he still scrambled to try and regain control. 

“Are- are you sure you don’t want any desert Sli-”

Papyrus didn’t get to finish his sentence. Slim’s hand gripped his tightly one second, and they were warping through time and space the next. He somehow managed to land on his feet, registered they were inside of a hotel room, then had Slim grabbing to slam him against the wall. Papyrus gasped in shock only to have his mouth filled with his boyfriend's tongue, making them both moan into the desperately needed kiss. Papyrus let Slim guide him, whimpering when their bodies slot together and felt that Slim was just as aroused as he was. Papyrus was so taken by the shift in pace that he almost forgot what caused it until he felt a wandering hand travel towards his chest. 

Slim groaned as his hand grasped as much of Papyrus breast as he could, breaking the kiss when Papyrus couldn’t control his moans. 

“Little Papy-” Slim teased breathlessly as he groped Papyrus through his top, the lust in his voice adding to the slick in Papyrus’s panties, “How did you- what made you think to-” 

A growl rumbled in Slim’s chest. He cut himself off with a hiss, pulling back and tearing Papyrus’s top clean off. It was a relief to have the constraints of such a tight top gone, but the feeling of being exposed so suddenly made Papyrus want to hide. Slim saw his blush growing as he squirmed in his hold and stopped what he was doing to grasp Papyrus’s skull. 

“You're so fucking hot.”

Papyrus writhed in embarrassment until Slim distracted him by moving to latch onto his neck. The familiar feeling of Slim’s fangs sliding against his vertebrae made Papyrus tingle, only for it to turn into a full body shiver when his hand started cupping his breast again. Without any barrier Papyrus could fee the roughness of Slim’s bones sliding against his flesh, the contrast in temperature making it hard to focus on anything else. 

“Ah! Slim! They’re really sensitive,” Papyrus warned, moaning again when Slim’s hand tightened in response. 

“Oh, really?” Slim snickered, the hand on Papyrus’s breast turning slightly so he could move his thumb over the nipple, “What about this?”

Slim rubbed his thumb in a few light circles, making Papyrus’s eyes roll in their sockets. 

“Mnnnnggg!!” 

_It felt so good!_ Slim was chuckling a Papyrus’s reaction, but it was all background noise at this point. Waiting to experience this with Slim first was both a blessing and a curse. Papyrs couldn’t control the way he keened at the slightest touch, or how hard his body was shaking in his lover’s grasp. His pussy was dripping with excited magic, each circle of Slim’s thumb sending a jolt of pleasure direct to his core. Within minutes Papyrus was grinding against Slim shamelessly, desperately seeking the friction of their magic through their clothes. Instinctively Papyrus raised a hand to his mouth to hide all the moans spilling out of his mouth only to have Slim immediately wrench it away.

“I’ve waited _so_ long, Papyrus.” Slim growled, thrusting his hips upwards to really drive his point home, “Don’t you dare hide.” 

Slim pinned both of Papyrus’s hands against the wall to grind into him properly. The direct stimulation was gone, but Papyrus only moaned louder when he felt the outline of Slim’s cock sliding against his drenched panties. He strained upwards to initiate another kiss, but Slim held him back, intent on watching Papyrus fall apart instead. They were so close, the denial felt like payback for the torment Papyrus had put Slim through either. With how worked up he was Papyrus couldn’t take being denied, whining inbetween each moan as Slim’s hot breath tickled his skull. It became apparent that Papyrus could no longer support his own weight and Slim thankfully had the sense to pick him clean off the floor and carry him towards the bed. 

Papyrus somehow lost the remainder of his top on the way, had his skirt pulled up, and his panties pushed aside. Slim remained fully clothed, but that didn’t stop Papyrus grinding his bare pussy against him as soon as he was pulled into his lap. Slim gasped and bucked into him, wrapping one arm around his back as the other hand found one of his breasts again. Papyrus’s skull felt like it was swimming as they moved together, each buck of his hips pushing him closer and closer to losing himself completely. 

Where Papyrus was falling apart, Slim knew exactly what he wanted. He let Papyrus hump him to his heart's content until he was begging for more between feverish kisses. Papyrus was pulled up and left shaking as Slim’s hand slipped in between them. He practically sobbed in need when he heard the sound of Slim’s zipper being undone. Papyrus pulled back into his boyfriend lap, gasping when he felt the heat of his boyfriend’s cock pressing at his entrance. Slim held him close and used his free hand to open Papyrus’s lips, allowing him to sink into the dripping magic with one firm thrust. 

Papyrus screamed when he felt his boyfriend bottom out inside him, unable to comprehend how amazing it felt. They’d waited so long to be together without any restrictions, and with Slim wanting to hear everything Papyrus planned on savouring every moment. He let himself whine when Slim pulled almost all the way out, only to rival Slim’s groan when he slammed him back down. Slim moved both arms around Papyrus, holding their bodys as close as possible as they rocked together. With both hands occupied, Papyrus was sure Slim’s attention would be pulled away from his chest. He was content with the feeling of being held close and breathed a sigh of relief over settling into something more familiar. 

He couldn’t have been more wrong. 

Slim took a few moments to set up a steady pace. It was different from their usual sessions, and with all the teasing back and forth, it didn’t make any sense that he’d want to go slow. Papyrus didn’t get a chance to question his boyfriend before Slim shifted their position, his mouth immediately attaching to one of Papyrus’s breasts. He moaned long and low as he was hit with an intense wave of almost unbearable pleasure. He could feel fangs lightly resting on his tender ecto, ready to bite at a moments notice, while Slim’s tongue circled around the hardened nipple. It was ecstasy, and Papyrus was set on letting the whole hotel know in spite of the soundproof walls. 

With the joint assault of pleasure inside and out Papyrus’s orgasm built embarrassingly fast, with Slim holding him so tightly he could do little to stop it. Papyrus threw his skull back as his body locked up, liquid magic squirting around Slim’s cock and filling his mouth. 

Wait- did that really-

_No!!_

It all happened so fast, Papyrus didn’t know if he’d imagined it or not until he saw Slim’s blown out eye lights. 

_And the line of orange magic dribbling down his mandible._

“I’m so sorry, I didn’t mean to- I didn’t know they could- Oh gosh, Slim, I’m so mmmF!”

Slim cut Papyrus off with a hand over his mouth. He waited for Papyrus to calm down with endless patience before taking the same breast in hand again. And squeezing. Papyrus watched with a mixture of shame and desire as more liquid magic leaked from his nipple, only to shudder when Slim lapped it up. If that wasn’t a dead giveaway for Slim’s true feelings on the matter, the hard cock twitching against Papyrus’s walls definitely was. 

“You really like it?” 

Papyrus knew the answer, but, he needed the extra reassurance more than anything right now. He didn’t know how it happened, convinced it was some flaw in the way he’d formed his breasts. But Slim drew back even more dazed than before, hardly able to keep his eye lights focused as he tried to look Papyrus head on. 

“Oh Papy, Fuck-” Slim growled and dug his fingers into Papyrus’s sensitive flesh, “I’m holding back from cumming inside your sweet cunt after that little taste.”

“ _Slim_ ” Papyrus scolded, “That’s so-” He was cut off again, this time by Slim’s mouth closing back around one of his breasts. “Mmmnngh, please, do it again!”

Slim’s response was to start moving inside him again, setting up a slow and deep pace that had Papyrus flailing from the assault on his senses. Slim built everything back up slowly, alternating between rolling Papyrus’s nipples between his fingers and suckling at the steady supply of magic. Papyrus was beside himself with how he should feel right now. It felt so intimate to have Slim pleasuring him this way, even if it was meant to be naughty. It definitely felt like a position he could take more of an active role in too, and it gave Papyrus back some of the confidence he’d been playing with earlier. If Slim was as into this as he was, then he wanted to make it a mutually beneficial experience. 

Papyrus tentatively brought his hand to the back of Slim’s skull to cradle it, his grip tightening when it spurred Slim on even more. He could feel his second climax working it’s way through his whole body, building slowly as he struggled to keep still. And Papyrus wasn’t the only one getting close. Looking down, he could see Slim’s sockets screwed shut, the teeth that could hurt Papyrus’s sensitive flesh smeared with magic. Papyrus had never seen Slim look so far gone before, the sight alone being enough to push him over the edge. 

Holding back was impossible at this point. Papyrus’s body shook violently with his second orgasm of the night as his lover moaned around him. Slim drew back, slamming Papyrus’s quivering body into his lap over and over until he was howling with his own release. He bottomed out again and held Papyrus close, pulling him into a final messy kiss. Aftershocks hit Papyrus hard when he tasted his own magic on Slim’s tongue. He kissed his boyfriend back just as hard as they rode their high till his vision became soft and fuzzy around the edges.

Papyrus didn’t know how long it took him to come down from the clouds, but Slim’s smirk greeted him when he returned. 

“See, you taste good, right?” Slim teased, wiping the excess magic from Papyrus’s mouth. 

Papyrus squeaked and hid his face in his hands. He couldn’t believe what they’d done, even less so that Slim was already joking about it. His beloved boyfriend laughed at his embarrassment, pulling Papyrus close again and accidentally making him aware just how hard he still was. Papyrus knew he’d be more than ready to go again, and that they had the entire weekend to indulge in all their urges. But the power trip had gone to his head. He jumped off Slim’s lap, falling to his knees and settled between his open legs.

Slim’s laughter was silenced when Papyrus placed his cock between the warm ecto of his still formed breasts. 

“I do,” Papyrus admitted, teasing the head of Slim’s cock with the tip of his tongue, “But I think you taste even better.”


End file.
